Yield monitoring system for grain harvesting combine

ABSTRACT

A yield monitoring system for a grain harvesting combine includes a volume monitor, a moisture monitor, a test weight monitor, a ground speed monitor, and a computer which receives signals from each monitor and continuously derives harvested grain yield rates from those signals, displays the yield rates on a visual display and records the yield rate information for later recall and transfer to other computers. A GPS receiver linked to the system enables it to map yields geographically in the harvested field. The volume monitor receives all grain exiting the clean grain elevator of the combine and passes it through a paddlewheel, the angular displacement of which is monitored over time. The moisture monitor and test weight monitor are mounted to the exterior of the clean grain elevator and receive samples of grain from the lift side of the clean grain elevator.

BACKGROUND OF THE INVENTION

This invention pertains to yield monitors for grain harvesters.Increasing emphasis is being placed on determination of crop yields asharvesting is being accomplished, particularly when the crop yield datais integrated with precise mapping of fields through use of a globalpositioning satellite receiver.

In the existing onboard yield measurement systems available for grainharvesters, harvested grain weight is measured by use of a verticalimpact plate positioned in the path of grain being discharged from anenclosed chain driven paddle conveyor commonly referred to as a cleangrain elevator of the grain harvester or combine. Such a measurementdevice is described in U.S. Pat. No. 5,343,761. This system hasshortcomings, namely baseline drift which occurs in the sampling must becorrected as described in U.S. Pat. No. 5,594,667. Also calibration isrequired at varying rates of flow, and inaccuracy cannot be eliminatedbecause test weight measurements of the grain are not available on areal time basis. For example, with existing apparatus, the weight ofcorn harvested is presumed to be fifty-six pounds per bushel at fifteenpercent moisture while the actual test weight of the corn may be muchdifferent. The condition and spacing of conveyor paddles, the varyingslope of the combine as it traverses a field, and the speed of the cleangrain elevator also can affect accuracy. A need exists for a yieldmeasurement system which periodically samples test weight of grain beingharvested and measures flow rate volume accurately at varying flowspeeds, in order to provide accurate input data for real timecalculation of yield rates within a field being harvested.

As part of the monitoring of crop yield, apparatus has been developed tomeasure crop moisture of samples of grain within the grain harvester orcombine, including devices which mount to the exterior of the cleangrain elevator of the grain harvester or combine. The clean grainelevator elevates grain from the separator of the combine to the onboardstorage tank of the combine which is located at the top of the combine.Current moisture sensors collect a sample of grain from the lift side ofthe clean grain elevator through an opening in the elevator housing andpass the grain into a vertical chamber in which a moisture sensor hasbeen mounted. Periodically the chamber is emptied by operation of amotor driven paddlewheel or auger which carries the grain from thechamber and drops it through an exhaust duct into the return side of theelevator housing so that a new sample can enter the chamber for moisturetesting. Once the combine is shut down, the operator must remember toenergize the paddlewheel or auger of the moisture test apparatus toempty it. If that is not done, grain will remain in the chamber and besubject to freezing or deterioration which may result in clogging of themoisture test apparatus. Downtime and inconvenience result from suchclogging, along with the danger from manually removing clogged grainfrom the moisture test apparatus. A need exists for an elevator mountmoisture sensor which resists clogging and which may be mounted on manydifferent makes and models of harvester.

SUMMARY OF THE INVENTION

A yield monitoring system for a grain harvesting combine is disclosed.The system includes a volume monitor, a moisture monitor, a test weightmonitor, a ground speed monitor, and a computer which receives signalsfrom each monitor and continuously derives harvested grain yield ratesfrom those signals, displays the yield rates on a visual display andrecords the yield rate information for later recall and transfer toother computers. A GPS receiver linked to the system enables it to mapyields geographically in the harvested field.

A volume monitor is positioned at the exhaust spout at the top of theclean grain elevator. The volume monitor receives all grain exiting theclean grain elevator and passes it on to a fountain auger that deliversit to the on board storage tank of the grain harvester combine. Thevolume monitor includes a receiving hopper which collects grain exitingthe clean grain elevator discharge port. An ultrasound level monitor ismounted above the hopper to detect and monitor the height of grain inthe hopper. The hopper includes a lower discharge chute which directsgrain onto a paddlewheel which may be driven at selectively varyingrotational speeds. The speed of rotation at which the paddlewheel isdriven is determined by a controller which causes the paddlewheel toturn sufficiently fast to maintain the grain at a steady leveldetermined by the level monitor. Hence when grain in the hopper is belowthe level determined by the level monitor, the paddlewheel is stoppedand when grain rises above the height determined by the level monitor,the paddlewheel is driven sufficiently rapidly so that grain in thehopper remains at the level determined by the level monitor. The angulardisplacement of the paddlewheel is measured and a signal is generatedwhich is provided to the computer. Because the volume capacity of thepaddlewheel to pass grain is predetermined, the angular displacementover time of the rotation of the paddlewheel provides information fromwhich volume of harvested grain over a time interval may be calculated.

The length of time interval for volume measurement may be selected overany range but a convenient interval for effective measurement is fromone to five seconds and in practice, the preferred interval is twoseconds, that is, the volume monitor provides volume of grain exitingthe clean grain elevator in two second increments, and the moisture andtest weight data are polled by the computer every two seconds.

The moisture monitor mounts to the exterior of the clean grain elevatorwithin the combine. A flexible entry duct which is open to the interiorof the lift side of the grain elevator is joined to the upper end of ahousing in which a moisture sensor is mounted. The housing is orientedvertically to hold a column of grain to be moisture tested. The lowerend of the housing opens to a non-motorized, compartmented wheelpreferably housing equally sized circumferential compartments ofpreselected size. The lower end of the housing is sized so that only onecompartment of the wheel may receive grain from the housing at one time.Free rotation of the wheel is prevented by a stop mechanism which inpractice may be a plunger which extends toward the wheel to prevent itsrotation. Momentary retraction of the plunger is controlled by a signalfrom a level sensor which is mounted in the housing above the moisturesensor to sense when grain in the housing reaches the level of the levelsensor. When grain is sensed by the level sensor, the plunger ismomentarily de-energized and retracts from the wheel, allowing the wheelto turn an incremental one-quarter rotation. Immediately thereafter, theplunger is energized and extends to stop further rotation of the wheel.Rotation of the wheel allows a fixed volume of grain to exit the housingwhich may then be refilled by grain falling from the lift side of theelevator into the housing through the entry duct. The moisture sensordetects moisture content in the column of grain and when polled by thecomputer provides a signal indicative of the level of moisture in thegrain.

After the grain passes the compartmented wheel, it may be exhausted intothe return side of the elevator through a flexible exhaust duct, or itmay be passed into a test weight measurement assembly which may belocated below the wheel so that the grain from the wheel may fall into acontainer of known tare weight. The grain in the compartment of thecompartmented wheel under the lower end of the housing is of apredetermined volume. This known volume of grain falls into thecontainer of the test weight measurement assembly. The container issuspended from a load cell which determines the weight of the grainwhich is in the container of the test weight measurement assembly.

In order to improve accuracy of the test weight measurement, a secondload cell is mounted near the first load cell with the second load cellsuspending a known weight equal to the standard test weight of apreselected volume of the grain to be harvested plus the known tareweight of the empty container. Coupling the test weight load cell outputwith the inverse of the output of the second load cell suspending theknown weight allows elimination of weighing errors due to vibration orjiggle of the load cells within the grain harvesting combine. Output ofthe combined load cells equals the difference in weight between themeasured test weight and the standard test weight.

Once the weight of the known volume of grain is determined and grain issensed by the level sensor, the container empties into the exhaust ductwhich returns the tested grain to the return side of the elevator.Emptying of the container may be done by providing the container with atrap door bottom which may be released to swing away and allow the grainto pass. After the container has been emptied, the trap door bottomcloses so that the container may receive the next sample of grain to beweighed. The trap door of the container opens and closes each timebefore the compartmented wheel is released to turn a quarter turn. Withthe test weight monitor option, the control signal from the level sensorto the compartmented wheel is delayed until the container is emptied andthe trap door closed.

The particular moisture monitor of the present invention has avertically oriented housing for temporarily holding a column of grain tobe moisture tested. The use of flexible ducting from the lift side ofthe clean grain elevator to the housing, and also from the dischargefrom the moisture monitor to the return side of the elevator allows themoisture monitor to be installed on many differing configurations ofclean grain elevator which may be found in different makes and models ofgrain harvesting combines. The novel discharge mechanism of the moisturemonitor additionally provides a moisture monitor housing whichautomatically is emptied upon equipment shut down because the stopmechanism plunger which restrains the wheel from rotation is retractedwhen it is de-energized, thereby permitting the wheel to rotate freelyto empty the housing of its column of grain. The test weight unit alsoempties upon shut down and the grain falls into the return side of theclean grain elevator.

A global positioning system (GPS) receiver is stationed on the grainharvesting combine to receive and store position information as well asto receive change-in-position information from which to calculatedirection and velocity information. The velocity information from theGPS receiver is transmitted to the computer to be used in the yieldcalculations. As an alternative, ground speed of the grain harvestingcombine may be obtained from well known transducer means mounted in thedrive gear of the combine. The electronic output of such a transducerwould be delivered to the central computer to be used for the groundspeed data.

As the computer receives the volume data, the moisture content data, theweight per bushel (test weight) data, the ground speed data, having beencalibrated for the swath of the harvester cutting head, the computer cancalculate the area harvested and the current yield in pounds (andbushels) per acre of dry grain equivalent, transfer the data to thedisplay for display to the operator, and transmit the data to anon-volatile memory device such as magnetic media or optical media(CD-ROM). Because the system is preferably integrated with GPS data,mapping of fields by yield may be accomplished.

It is an object of the invention to provide a yield monitoring systemfor a grain harvester which provides real time yield information at ahigh level of accuracy independent of harvester variables.

It is a further object of the invention to provide a yield monitoringsystem which determines actual test weight in pounds per bushel of cropgrain as it is harvested.

It is a further object of the invention to provide a yield monitoringsystem which provides an accurate measurement of volume of crop grainbeing harvested per unit of time.

It is yet a further object of the invention to provide a yieldmonitoring system which generates real time yield data at known fieldlocations.

It is yet another object of the invention to provide a moisture monitorwhich mounts to many different combine clean grain elevators withoutsubstantial modification.

It is yet another object of the invention to provide a moisture monitorwhich prevents clogging of the moisture monitor when it is not inoperation.

It is a further object of the invention to provide a weighing apparatususing two load cells to eliminate weighing errors due to vibration ofthe combine in which weighing of the grain is to be accomplished.

These and other objects of the invention will become apparent fromexamination of the detailed description and drawings included in thisspecification.

DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a schematic diagram of the preferred embodiment system forcalculating yield of grain harvested per acre on a real time basis.

FIG. 2 is a front elevation of a clean grain elevator of a grainharvesting combine equipped with an improved moisture and test weightmonitor and an improved flow rate monitor with the case of the cleangrain elevator partly cut away to illustrate the interior of the cleangrain elevator.

FIG. 3 is a front elevation of the flow rate monitor of the inventionmounted at the outlet of the clean grain elevator, with the coverremoved to show the interior of the flow rate monitor.

FIG. 4 is a front elevation of the moisture monitor and test weightmonitor of the preferred embodiment with the outer case cut away to showthe interior features of the devices.

FIG. 5 is a side plan view of the paddlewheel of the flow rate monitorof the preferred embodiment of the invention.

FIG. 6 is a side plan view of the wheel of the moisture and test weightmonitor component of the invention.

FIG. 7 is an enlarged side plan view of the paddlewheel and the grate ofthe flow rate monitor component showing interaction of a fin of thepaddlewheel with the grate.

FIG. 8 is an electrical schematic of the preferred embodiment of thetest weight measurement apparatus of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a yield monitoring system for a grainharvesting combine which allows real time determination and mapping ofyield data as the combine passes through the field. FIG. 1 diagrams thesystem invention and illustrates that a central signal processor 2 iscoupled to a moisture sensor 4, a test weight monitor 6, a grain flowmeter 8, and a DGPS receiver 10, all of which provide input data to thesignal processor 2. The DGPS receiver 10 receives signals from an arrayof earth orbiting satellites from which coordinates on the surface ofthe earth can be determined, along with direction of movement and groundspeed of the receiver. Signals from an earth based antenna at aprecisely known location may also be received by the DGPS receiver toenhance accuracy of calculated location from coordinate data receivedfrom the earth orbiting satellites. The DGPS receiver 10 may provide tothe signal processor the ground speed of the combine and it may provideposition data which may be linked to yield data calculated by the signalprocessor from the moisture sensor 4, the test weight monitor 6 and theflow rate meter 8. Ground speed information may also or alternatively beprovided to the signal processor 2 from a ground speed sensor 12 mountedto the transmission or other drive line component of the combine whichcounts revolutions of drive line components from which ground speed canbe determined.

A keyboard 14 is coupled to the signal processor for operator datainput, including for entering the width of the cutting head of thecombine. The swath width is used with the ground speed data from theDGPS receiver 10 or the ground speed sensor 12 to calculate the areaharvested over unit of time. A touch screen display 16 is coupled to thesignal processor 2 and may be used both to receive operator inputs andselections and to visually display yield rate information. Anon-volatile memory 18, such as a storage device which will store dataon magnetic or optical media, is coupled to signal processor 2 toreceive and store yield data and location data for later use and fortransmission or transport to other computing devices.

The moisture sensor 4 samples grain moving within the combine todetermine the moisture content of the grain and provides this sampleddata to the signal processor 2. The test weight monitor 6 also takessamples of grain periodically and weighs a known volume of the sampledgrain to determine the test weight of grain moving within the combine.The test weight data is transmitted to the signal processor 2 by thetest weight monitor 6. Grain flow data on a volume per time intervalbasis is collected by the flow rate meter 8 on a continuous basis andthis grain flow data is provided to the signal processor 2 to be used tocalculate pounds and/or bushels per acre corrected for moisture contentand for test weight variance. For example, the standard test weight forcorn (maize) is fifty-six pounds per bushel and the market moisturecontent is fifteen percent. Specifically, the moisture sensor 4 isperiodically polled by the signal processor 2 for the moisture contentof the last sample of grain tested by the moisture sensor 4. The testweight monitor 6 is also periodically polled by the signal processor 2for the last test weight determined for a specified volume sample ofgrain. The flow rate meter 8 provides an ongoing stream of dataindicating the volume of grain exiting the clean grain elevator per unitof time. The DGPS receiver 10 or the ground speed sensor 12 provides anongoing indication of the ground speed of the combine. From these datainputs the signal processor 2 may calculate the actual weight and volumeper unit area (typically acres) of the grain being harvested and maycorrelate the yield data to geographic coordinates and cause display ofsuch information on the display 16 and store it on the non-volatilememory 18.

Referring now to FIG. 2, the moisture monitor 4, test weight monitor 6and flow rate meter 8 of the preferred embodiment may be seen mounted tothe clean grain elevator 20 of a typical combine. The clean grainelevator 20 conveys grain 26 from the threshing machinery within thecombine to the grain storage tank mounted at the top of the combine, asis well known in the art and not further illustrated in this disclosure.

A section of the case 22 of clean grain elevator 20 has been cut away inFIG. 2 to show the paddles 24 which elevate grain 26 on the lift side 28of clean grain elevator 20. Paddles 24 are carried by continuous chain30 which also lowers paddles 24 on return side 32 of clean grainelevator 20. A separating wall 34 is vertically disposed to separatelift side 28 from return side 32 of clean grain elevator 20. Themoisture sensor 4 includes housing 36 to which is coupled an intake duct38 which is preferably a flexible or bendable tube with low frictioninner surfaces which is in communication with the lift side 28 of cleangrain elevator 20 such that some units of grain 26 may freely fall intointake duct 38 and pass into housing 36. Stationed below moisturemonitor 4 is test weight monitor 6 which may receive grain passedthrough housing 36 of moisture monitor 4. Grain received in test weightmonitor 6, after weighing, may fall into funnel 40 and be returned tothe return side 32 of clean grain elevator 20 via return duct 42 whichis also a flexible tube which communicates through case 22 with thereturn side 32 of clean grain elevator 20. The use of flexible tubes forintake duct 38 and return duct 42 allows the moisture monitor 4 and testweight monitor 6 combination to be mounted to the clean grain elevatorof combines of various makes and models.

A level sensor 44 is mounted to housing 36 near intake duct 38. Moisturesensing unit 46 is mounted to housing 36 below level sensor 44 and abovewheel housing 50. A solenoid unit 48 is mounted upon wheel housing 50 toselectively control passage of grain in housing 36 into test weightmonitor 6.

The flow rate meter 8 of the preferred embodiment system is positionedat the exit outlet 54 of the clean grain elevator 20 at upper end 56thereof such that all grain leaving the clean grain 20 elevator passesinto the flow rate meter 8. Flow rate meter 8 includes an intake hopper58 into which grain leaving the clean grain elevator is received. Grain26 which has passed through flow meter 8 exits through discharge chute60 and may pass to a fountain auger (not shown) which may be locatedwithin the grain storage tank of the combine.

A motor 64 is mounted near flow meter 8 for powering thereof. Rotationsensor 62 is mounted to flow meter 8 to measure the angular displacementof flow meter 8 and to provide such data to the signal processor 2.

FIG. 3 illustrates the preferred embodiment flow rate meter 8 with itsfront cover removed so that internal components thereof may beunderstood. Flow rate meter 8 comprises a paddlewheel 66 having radiallydisposed multiple fins 68 which in the preferred embodiment aregenerally equally angularly spaced. Paddlewheel 66 is selectively drivenin a clockwise direction by variable speed motor 64 which is preferablya DC motor powered by the electrical system of the combine. Variablespeed motor 64 drives paddlewheel 66 at varying rates of rotationwherein the level of grain 26 in bin 70 is maintained generallyconstant. Grain 26 is allowed to fall freely through grate 72 into equalvolume sectors 74 of paddlewheel 66 defined by adjacent fins 68.Paddlewheel 66 is rotatively driven about an axis defined by drive shaft76 thereof which in the preferred embodiment is disposed generallyhorizontally. Paddlewheel 66 is housed in cylindrical housing 78 whichis provided with an opening into discharge 80. The level of grain 26present in bin 70 above paddlewheel 66 is sensed by a height detector 82mounted within the top cover 86 of bin 70, height detector 82 preferablybeing an ultrasound transducer 84 which detects the level of grain 26 inbin 70. Other types of height detectors 82 may be used. When grainpresent in bin 70 rises above a predetermined level, height detector 82transmits a control signal which causes the speed of variable speedmotor 64 to increase, thereby driving paddlewheel 66 at an increasedspeed in order to more rapidly transfer grain 26 from bin 70 todischarge 80 in order to lower the level of grain 26 in bin 70. Whenheight detector 82 senses a lowering of the level of grain 26 in bin 70,it signals variable speed motor 64 to drive paddlewheel 66 at a slowerrate to slow passage of grain 26 from bin 70. This feedback operation ofmotor 64 and height detector 82 thereby maintains the level of grain 26in bin 70 above grate 72 at a consistent, predetermined level.

The rotational movement of paddlewheel 66 is measured by rotation sensor62 and the angular displacement of paddlewheel 66 over time istransmitted by rotation sensor 62 to the signal processor 2 which maycalculate the volume of grain exiting the clean grain elevator 20 as afunction of time. Because the volume of each of sectors 74 ofpaddlewheel 66 is known, the volume of harvested grain 26 per unit oftime exiting clean grain elevator 20 may be calculated. Any timeincrement may be utilized for such determination but it is found that auseful time interval is in the range of one to five seconds, and morepreferably about two seconds, in which period the moisture and testweight of grain samples is collected. The volume per time calculationresulting from measurement of the rotation of paddlewheel 66 provides agrain yield result which must be corrected to a market moisture contentand standard weight per bushel of the grain type being harvested.

Referring additionally to FIGS. 5 and 7, the features of paddlewheel 66and its interaction with grate 72 may be visualized. Paddlewheel 66 maybe driven by variable speed motor 64 by use of belt 90 or by gears whichinterconnect motor shaft 88 with drive shaft 76 of paddlewheel 66.Rotation sensor 62 is coupled to drive shaft 76 such that the angulardisplacement of paddlewheel 66 may be measured and transmitted to thesignal processor 2.

Each of fins 68 of paddlewheel 66 has a free edge 92 which is providedwith a multiplicity of spaced apart relatively stiff brushes 94 whichmay deflect slightly when an item of grain is caught between a brush 94and the inside of cylindrical housing 78. The placement of brushes 94along edges 92 of fins 68 is prescribed by the spaces between bars 96 ofgrate 72. Preferably bars 96 are triangular in cross section with thevertices 98 thereof oriented upwardly so that grain may be funneledthrough grate 72 and evenly deposited in sectors 74 of paddlewheel 66.Brushes 94 are sized to extend from edges 92 such that brushes penetratevery slightly into the spaces between bars 96 of grate 72, therebyserving to wipe grain units into sectors 74 without damage to the grainunits.

Referring now to FIGS. 4 and 6, the moisture sensor 4 and test weightmonitor 6 may be seen in more detail. Intake tube 38 feeds grain 26 fromlift side 28 of clean grain elevator 20 into vertically oriented housing36. A moisture sensing unit 46 is mounted along housing 36 such thatsensing probe 106 is exposed to grain 26 within housing 36. Moisture ingrain 26 causes moisture sensing unit 46 to respond with an electricalsignal proportional to the percentage of moisture in the grain and thiselectronic signal is transmitted to the signal processor 2 duringperiodic polling by signal processor 2.

Disposed partially in alignment below housing 36 is wheel 108 housedwithin wheel housing 50. Wheel 108 is provided with a multiplicity ofcircumferential compartments 110 separated by blades 112 which radiatefrom central hub 102. Blades 112 are angularly equidistant and number atleast four and preferably a multiple of four such that the wheel 108 maybe turned in one-quarter turn increments and convey the same volume ofgrain for each quarter turn. The compartments 110 are sized such thatone-fourth rotation of wheel 108 will convey a known fraction of abushel or other suitable volume measure of grain 26. Wheel 108 islimited in its rotation by interaction of spoke wheel 104 with solenoidplunger 116 which extends to intercept one of spokes 114 when solenoidunit 48 is energized. Spoke wheel 104 is fixed to hub 102 such thatrotation of spoke wheel 104 coincides with rotation of wheel 108. Wheelhousing 50 is open where it meets lower end 118 of housing 36 such thatgrain 26 in housing 36 will be stored in compartments 110 of wheel 108while wheel 108 is prevented from rotating. When grain 26 rises inhousing 36 to the level of level sensor 44, level sensor 44 senses thegrain and issues a signal to solenoid 48 to momentarily de-energize forsufficient duration for wheel 108 to rotate in a counterclockwisedirection one-quarter turn thereby transferring a known volume of graininto open topped container 120. Container 120 is fed by guide chute 122disposed below wheel 108. As wheel 108 rotates, the contents of filledcompartments 110 are dumped into guide chute 122 and empty compartments110 of wheel 108 are moved into position below housing 36 and fill bygravity with grain, thereby dropping the level of grain 26 below levelsensor 44.

When grain 26 drops from wheel 108 into container 120, bottom 124thereof is retained in its closed position by action of trap doorcontroller 132. While resting on bottom 124 of container 120, grain 26of known volume in container 120 may be weighed by first load cell 126.Because of vibration and jiggle within the combine, and variations ofslope or tilt of the combine as it travels over uneven ground, error inweighing may occur which is compensated for by comparative weighing ofdummy weight 128 by second load cell 130. Dummy weight 128 is preferablychosen to be equal to the standard test weight of a predetermined volume(equal to the known volume conveyed in one quarter turn of wheel 108) ofthe grain to be harvested plus the tare weight of container 120 whenempty such that the measured weight from second load cell 130 may becompared with the measured weight of first load cell 126 to determinethe test weight of the known volume of harvested grain 26 present incontainer 120. This measured grain test weight is stored in associatedcircuitry and made available for polling by signal processor 2 until anew sample of grain 26 is placed in container 120 and its weightdetermined and stored.

When level sensor 44 detects grain, level sensor 44 first signals trapdoor controller 132 to extend prior to signaling solenoid 48 tode-energize, thereby permitting the bottom 124 of container 120 to swingdownward allowing the contents of container 120 to fall into funnel 40to thereafter fall through return duct 42 into return side 32 of cleangrain elevator 20. Trap door controller 132 promptly returns bottom 124to its closed position and wheel 108 is then permitted to rotate torefill container 120 with a new grain sample. An interlock memberintercoupling trap door controller 132 and solenoid unit 48 preventssolenoid plunger 116 from retracting while bottom 124 is not retained ina closed position by trap door controller 132.

Once flow rate data has been generated by the signal processor 2 fromthe angular displacement per unit time of paddlewheel 66 as measured byrotation sensor 62 of flow rate meter 8, the raw yield rate may bedetermined by dividing the flow rate by the product of ground speed ofthe combine and the swath of the combine cutter head. This raw yielddata can then be corrected to a standard yield rate in pounds (andbushels) per acre of dry grain by adjusting the volume per unit area(bushels per acre) of wet grain to a standard market moisture and to astandard market weight (for example, the standard market weight for cornat fifteen percent moisture is fifty-six pounds per bushel) from themoisture data provided by the moisture sensor 4 and from the test weightdata provided by the test weight monitor 6. The resulting standard yielddata may then be displayed on the display 16 for review by the combineoperator and it may be integrated with coordinate data provided by theDGPS receiver 10 and stored on the non-volatile memory 18 for laterreview or for transfer to external computing and display devices. Hencethe system invention may provide real time yield data with increasedaccuracy over other methods since approximation of grain test weight isavoided and calibration adjustments for speed and condition of the cleangrain elevator 20, and for variation of the grain flow rate, terrainslope, and grain quality, are not required.

FIG. 8 illustrates an electrical schematic for the test weight monitor 6of the system invention. Voltage regulator 140 regulates the combine'sonboard 12 VDC voltage to a convenient 10 VDC which is used asexcitation voltage for first load cell 126 and for second load cell 130.A satisfactory load cell unit for use for first load cell 126 and secondload cell 130 may be an OMEGA™ LCL-454G full bridge load cellmanufactured by OMEGA Engineering, Inc. of Stamford, Conn. The OMEGA™LCL-454G load cell has a rated capacity of sixteen ounces and a ratedoutput of two millivolts per volt of excitation voltage (twentymillivolts output at full scale deflection or 1.25 millivolts per ouncewith 10 VDC excitation). Second load cell 130 suspends dummy weight 128which is predetermined to be equal to the standard test weight of apredetermined volume of the grain to be harvested plus the tare weightof the container 120 when empty. Dummy weight 128 may be preset at nineounces such that second load cell 130 will generate 11.25 millivoltsreferenced to ground at second terminal 138 when second load cell 130 is3 excited with 10 VDC. If test container 120 holds seven ounces of grainprecisely at standard test weight and market moisture content andcontainer 120 weighs two ounces, then first load cell 126 will deliver11.25 millivolts referenced to ground at first terminal 136 when firstload cell 126 is excited by 10 VDC. Voltmeter 134 measures the potentialdifference between the output voltage of first load cell 126 at firstterminal 136 and the output voltage of second load cell 130 at secondterminal 138 and this voltage difference is directly related to the testweight of the predetermined volume of grain held in container 120 whenits bottom 124 is closed. Because dummy weight 128 is preselected to beapproximately the same mass as that of container 120 filled with a grainsample of known volume to be weighed, vibration and jiggle within themoving combine will be substantially offset and the potential differencedetected by voltmeter 134 will represent the weight difference betweenfilled container 120 and dummy weight 128 and this weight difference canbe combined with the known weight of dummy weight 128 and the totalreduced by the tare weight of the container 120 to obtain the testweight of the grain sample weighed.

Having described the invention, I claim:
 1. A yield monitoring systemfor a grain harvesting machine having a grain storage bin and a cleangrain elevator, the clean grain elevator having an exterior and aninterior and an upper discharge port, comprising, a grain flow monitordisposed adjacent the discharge port of said clean grain elevator andreceiving all grain discharged from said upper discharge port, the grainflow monitor comprising a hopper and a rotatable paddlewheel disposedbelow said hopper, a sensor disposed upon said hopper above saidpaddlewheel, said sensor generating a first control signal responsive todetection of grain at a predetermined level in said hopper, saidpaddlewheel selectively controlled by said first control signal torotate sufficiently rapidly to maintain grain above said paddlewheel atthe predetermined level in said hopper, an angular displacement monitorresponsive to rotation of said paddlewheel and generating a first datasignal responsive to the rotation of said paddlewheel over unit of time,a moisture sensor member mounted within said grain harvesting machine,said moisture sensor member coupled to said clean grain elevator toreceive grain moving in said clean grain elevator, the moisture sensormember including a housing having an upper end and a lower end, saidhousing having a moisture detector disposed therein, said moisturedetector responsive to moisture content of grain in said housing togenerate a second data signal proportional to said moisture content ofsaid grain, a non-driven rotatable wheel supported below said lower endof said housing, said wheel having circumferentially disposedcompartments thereon, said wheel selectively rotatable whereby rotationof said wheel allows grain to be discharged from said lower end of saidhousing, a computer receiving said first data signal from said angulardisplacement monitor and said second data signal from said moisturesensor, the computer receiving a ground speed signal dependent upon theground speed of said grain harvesting machine, said computer generatingyield output data from said first data signal, said second data signaland said ground speed signal, a display coupled to said computer forreceiving and displaying said yield output data.
 2. The system of claim1 wherein said wheel is selectively incrementally rotatable wherebyincremental rotation of said wheel allows a predetermined volume ofgrain to be discharged from said lower end of said housing, a containerdisposed below said wheel for receiving said predetermined volume ofgrain discharged from said housing, a load cell supporting saidcontainer and producing a third data signal proportional to the weightof said predetermined volume of grain in said container, said containerhaving a selectively opened bottom whereby grain in said container maybe emptied from said container, said computer coupled to said load cellto receive said third data signal from said load cell.
 3. The system ofclaim 2 wherein said motorless elevator mounted moisture sensor memberis mounted to the exterior of said clean grain elevator, said housing ofsaid moisture sensor member being vertically disposed, a first ductinterconnecting said interior of said elevator and said upper end ofsaid housing, the upper end of said housing communicative with saidfirst duct to receive grain from the interior of said clean grainelevator, said moisture detector mounted to said housing above saidlower end thereof, a plunger selectively engaging said wheel to preventrotation thereof, a level detector mounted within said housing abovesaid moisture sensor, the level detector responsive to grain within saidhousing, said level detector generating a second control signal whengrain is detected by said level detector, said plunger responsive tosaid second control signal of said level detector to temporarilydisengage from said wheel to permit limited rotation thereof, a secondduct disposed below said bottom of said container to receive grainemptied from said container, said second duct in communication with theinterior of said clean grain elevator.
 4. The system of claim 3 whereinsaid first duct and said second duct are constructed of flexible tubing.5. The system of claim 3 wherein a transducer is coupled to said grainharvesting machine to measure ground speed of said grain harvestingmachine, said transducer is coupled to said computer to provide saidground speed signal.
 6. The system of claim 3 wherein a mechanismselectively retains said bottom of said container in a closed position,said level detector coupled to said mechanism and said plunger, saidmechanism responsive to said second control signal of said leveldetector to release said bottom of said container from its closedposition, an interlock member prevents rotation of said wheel when saidbottom of said container is open.
 7. The system of claim 2 wherein aglobal positioning system receiver is coupled to said computer, saidglobal positioning system receiver generating location information fromreceived signals from an array of earth orbiting satellites, saidcomputer integrating said location information from said globalpositioning system receiver with said yield output data.
 8. The systemof claim 7 wherein said global positioning system receiver generatessaid ground speed signal.
 9. The system of claim 2 wherein a keyboard iscoupled to said computer, said keyboard operable to input information tosaid computer, a non-volatile storage member is coupled to said computerto receive and store yield output data for later review.
 10. The systemof claim 9 wherein said non-volatile storage member includes removablestorage media therein.
 11. A motorless elevator mounted moisture sensorfor mounting to the exterior of a clean grain elevator of a grainharvester, the elevator having an internal lift side and a return sidehoused in a case, comprising a vertically disposed housing having anupper end and an open lower end, a first duct in communication with saidlift side of said elevator and the upper end of said housing to passgrain into said housing, a non-driven rotatable wheel supported belowsaid lower end of said housing, said wheel covering said open lower endof said housing, a plunger selectively engaging said wheel to preventrotation thereof, said wheel having circumferentially disposedcompartments thereon, a moisture sensor mounted in said housing abovesaid lower end, the moisture sensor responsive to moisture content ofgrain in said housing to generate a first data signal proportional tosaid moisture of said grain, a level detector mounted within saidhousing above said moisture sensor, the level detector responsive tograin within said housing, said level detector generating a firstcontrol signal when grain is detected by said level detector, saidplunger responsive to said first control signal of said level detectorto temporarily disengage from said wheel to permit limited rotationthereof, a hopper disposed below said wheel to receive grain moved bysaid wheel, a second duct communicative with said hopper and said returnside of said elevator.
 12. The moisture sensor of claim 11 wherein, saidwheel is selectively incrementally rotatable whereby incrementalrotation of said wheel allows a predetermined volume of grain to bedischarged from said lower end of said housing, a container disposedbelow said wheel for receiving said predetermined volume of graindischarged from said housing, a load cell supporting said container andproducing a third data signal proportional to the weight of saidpredetermined volume of grain in said container, said container having aselectively opened bottom whereby grain in said container may be emptiedfrom said container.
 13. The moisture sensor of claim 11 wherein, saidfirst duct comprises a flexible tube.
 14. The moisture sensor of claim11 wherein, said second duct comprises a flexible tube.
 15. A testweight sensor for mounting to the exterior of a clean grain elevator ofa grain harvester, the elevator having an internal lift side and areturn side housed in a case, comprising a vertically disposed housinghaving an upper end and an open lower end, a first duct coupling saidlift side of said elevator to the upper end of said housing, anon-driven rotatable wheel supported below said lower end of saidhousing, said wheel covering said open lower end of said housing, aplunger selectively engaging said wheel to prevent rotation thereof,said wheel having circumferentially disposed compartments thereon, saidcompartments of predetermined volume, a level detector mounted withinsaid housing above said lower end thereof, the level detector responsiveto grain within said housing, said level detector generating a firstcontrol signal when grain is detected by said level detector, saidplunger responsive to said first control signal of said level detectorto temporarily disengage from said wheel to permit limited rotationthereof, a container disposed below said wheel of said housing forreceiving a predetermined volume of grain discharged from said housing,the load cell suspending said container and producing a weight datasignal proportional to the weight of said predetermined volume of grainin said container, said container having a selectively opened bottomwhereby grain in said container may be emptied from said container to asecond duct, said second duct in communication with the return side ofsaid clean grain elevator.
 16. The test weight monitor of claim 15wherein, a moisture sensor is mounted in said housing above said lowerend, said moisture sensor responsive to moisture content of grain insaid housing to generate a first data signal proportional to saidmoisture of said grain.
 17. The test weight monitor of claim 15 wherein,a second load cell is disposed in proximity to said load cell, thesecond load cell suspending a dummy weight of known weight, said secondload cell generating a second voltage responsive to the weight of thedummy weight, a voltmeter coupled to said first load cell and saidsecond load cell to measure the potential difference between said firstvoltage and said second voltage.
 18. A grain flow monitor for measuringvolume flow rate of grain discharged by a power driven conveyor in agrain harvester, comprising a hopper having an open top and an openbottom, said hopper disposed to receive all grain discharged by saidconveyor, a rotatable paddlewheel disposed below said hopper andcovering said open bottom of said hopper, said paddlewheel having amultiplicity of compartments circumferentially mounted thereon, eachcompartment of predetermined volume, a height sensor disposed upon saidhopper above said paddlewheel, said height sensor generating a controlsignal responsive to the height of grain in said hopper, saidpaddlewheel selectively controlled by said control signal to rotatesufficiently rapidly to maintain grain at a predetermined height withinsaid hopper, an angular displacement monitor responsive to the rotationof said paddlewheel generating a first data signal responsive to therotation of said paddlewheel over unit of time, a computer receivingsaid first data signal and calculating therefrom a volume flow rate ofgrain exiting said conveyor, said computer coupled to a storage mediumfor receiving and storing said volume flow rate, a grate member isdisposed at the open bottom of said hopper, said grate member having amultiplicity of bar members, said bar members each spaced apart fromsaid other bar members, said paddlewheel having paddles separating saidcompartments thereof, each of said paddles having a free outer edge,each of said free outer edges of said paddles having a plurality ofbrush members disposed thereon, each of said brush members in registrywith a space between adjacent ones of said bar members.